HomeMy WebLinkAbout4.4 TOWN OF Los ALTOS HILLS April 26, 1995
Staff Report to the Planning Commission
RE: SITE DEVELOPMENT PERMIT FOR A NEW RESIDENCE AND
POOL; LANDS OF WARD; 11841 FRANCEMONT DRIVE.
FROM: Suzanne Davis, Planner SD
RECOMMENDATION That the Planning Commission:
Approve the requested Site Development Permit as submitted, subject to the
attached conditions of approval.
BACKGROUND
The subject property is parcel 2 of the Bellucci Subdivision (Francemont Estates).
The parcel is a flag lot with access from Francemont Drive. There is a storm
drain and conservation easement along the northerly property line where Adobe
Creek runs through the lot.
There are a number of subdivision improvements which have not yet been
completed. While the applicant can receive approval of the proposed projects
(new residences and pools are also proposed on parcels 1 and 3), no building
permits can be issued until the required improvements are completed to the
satisfaction of the Town Engineering Department (see condition#17).
DISCUSSION
Site Data:
Net Lot Area: 1.14 acres
Average Slope: 14.7%
Lot Unit Factor: 1.03
Floor Area and Development Area:
Area Max. Prop. Exist. Incrs. Left
Devel. 13,635 11,552 -0- 11,552 +2,083
Floor 5,938 5,864 -0- 5,864 +74
The applicant is requesting approval of a single-story residence and a swimming
pool. The maximum height of the house will be 24 feet as measured from the
existing grade. The property has several feet of fill which was required since the
lot is within a flood plain. The elevations show the original grades prior to the
,
Planning Commission
April 26, 1995 '
Lands of Ward/parcel 2
Page 2
fill being placed on the site and the finished grade. Proposed exterior materials
are stucco siding,wood windows and doors and tile roofing. There are also four
small skylights proposed. Required parking include the three spaces in the
attached garage, and one uncovered space within the circular turnaround.
The house has been located five feet from the conservation easement as
recommended by staff. This will allow a walkway to be installed, and grading
and construction to take place without encroaching into the conservation
easement. Although the proposal will leave less than 100 square feet of MFA,
there is about 2,000 square feet of development area remaining for future
improvements.
The applicant has included a conceptual landscape plan with the development
plans to show proposed plantings for screening of the new residence and pool.
The final landscape plan will be reviewed by the Site Development Committee
once the house is framed.
The Santa C ValleyWater District has reviewed the plans and has found the
proposed construction acceptable. The applicant will be required to have
SCVWD review and approve the construction drawings prior to acceptance of
plans for building plan check.
Grading volumes total 506 cubic yards (88 cu. yds. of cut and 418 cu. yds. of fill).
Approximately 330 cubic yards of material will need to be imported to the site.
There will be excess cut from parcel 1 which can be moved to parcel 2. The
project engineer will attempt to balance the cut and fill for the three parcels so
that trucking of material in or out of the area will not be necessary. The
Engineering Department has reviewed the plans and has recommended
conditions as specified in Attachment 1.
There is a portion of the proposed driveway turnaround area which is within the
setback. This is an area which has been of recent concern to the planning
Commission[ If the Commission feels that the amount of paving within the
setback is not acceptable, the applicant should be directed to change the design
accordingly. In addition to driveway area there is 210 square feet of pool
decking within the setback (the Zoning Ordinance allows up to five feet of
decking to encroach into the setback). A condition of approval should be added
if the Commission decides to require any changes to the driveway or other
aspects of the project.
The Town Geologist has conducted an extensive review of the site and
geotechnical reports, and has recommended approval of the project subject to
conditions (see Attachment 3). The Fire Department has no recommended
conditions.
Planning Commission
' April 26, 1995
Lands of Ward/parcel 2
Page 3
The Pathways Committee recommendation states that the old lodge entrance
road be regraded so that it drains into Adobe Creek instead of forming a pond.
This grading will be completed as part of the subdivision improvements. A
native pathway easement is requested over that route, along Adobe Creek and a
IIB path is requested along the remainder of the Moody Road frontage. The IIB
path will be installed as part of the subdivision improvements. For this reason
condition#16 states that the IIB path shall be rehabilitated as necessary,prior to
final inspection.
Staff is available to answer any questions that the Commission or community
may have.
ATTACHMENTS:
1. Recommended conditions of approval
2. Letter from William Cotton &Associates dated December 19, 1994 (four
pages)
3. Letter from William Cotton & Associates dated March 8, 1995 (four pages)
4. Letter from Santa Clara Valley Water District received December 21, 1994
(one page)
5. Pathways Committee recommendation dated January 25, 1995 (one page)
6. Revised development plans: topographic survey, site plan, elevations, floor
plans, roof plan and conceptual landscape plan (five sheets)
cc: Jim Ward &Associates
99 El Camino Real
Menlo Park, CA 94027
The WB Group
4151. Middlefield Road, Suite 115
Palo Alto, CA 94303-4743
Tom Scherer
413 Capitola Avenue
Capitola, CA 95010
1
Planning Commission
April 26, 1995
Lands of Ward/parcel 2
Page 4
ATTACHMENT 1
RECOMMENDED CONDITIONS FOR SITE DEVELOPMENT PERMIT
FOR NEW RESIDENCE AND POOL
LANDS OF WARD, 11841 FRANCEMONT DRIVE
A. PLANNING DEPARTMENT:
1. Any changes or modifications to the approved plans shall be
approved by the Planning Director or the Planning Commission,
depending upon the scope of the changes.
2. The property owner shall inform the Town of any damage and
shall repair any damage caused by the construction of the project to
pathways, private driveways, public and private roadways prior to
final inspection and release of occupancy permits and shall provide
the Town with photographs of the existing conditions of the
roadways and pathways prior to acceptance of plans for building plan
check.
3. Prior to final inspection the final landscape planting plan shall be
submitted for approval by the Site Development Committee. The
Committee may require a bond, a landscape maintenance
agreement, or other security to assure that the approved landscape
is planted and maintained. Outdoor lighting shall be reviewed
with the landscape plan.
4. A grading and construction operation plan shall be submitted by
the property owner for review and approval by the City Engineer
and Planning Director prior to submittal of plans for building plan
check. The grading/construction operation plan shall address truck
traffic issues regarding dust, noiseand vehicular and pedestrian
traffic safety on Francemont Drive, Moody Road and surrounding
roadways; storage of construction materials; placement of sanitary
facilities; parking for construction vehicles; and parking for
Construction personnel. A debris box (trash dumpster) shall be
placed on site for collection of construction debris. Arrangements
Must be made with the Los Altos Garbage Company for the debris
box, since they have a franchise with the Town and no other hauler
is allowed within the Town limits.
5. Skylights shall be designed and constructed to reduce emitted light.
No lighting may be placed within the skylight wells.
Planning Commission
April 26, 1995
Lands of Ward/parcel 2
Page 5
6. Paint color shall be chosen by the applicant and approved by staff
in conformance with the Town's adopted color board. A color
sample shall.be submitted to the Planning Director for approval
prior to painting the exterior of the residence.
7. Fire retardant roofing is required for the residence.
8. Standard swimming pool requirements:
a. Lights shall be designed so that the source is not visible from
off-site.
b. Drainage outfall structures shall be constructed and located to
the satisfaction of the Town Engineering Inspector.
c. Fencing or a locking pool cover is recommended for safety.
d. Equipment shall be enclosed on all four sides and roofed for
noise mitigation.
9. A deed restriction shall be recorded which states that the 5,864
square feet of floor area (MFA) approved under this permit is close
to the maximum level of development currently allowed by the
Town, and that any further expansion must be approved by the
Town. The deed restriction will be prepared by the Planning
Department, and the signed, notarized document shall be returned
to the Town prior to acceptance of plans for building plan check.
B. ENGINEERING DEPARTMENT:
10. All conditions recommended by William Cotton & Associates'
report dated March 8, 1995, are conditions of this permit. A letter
of compliance prepared by the geotechnical consultant (regarding
the construction plans) shall be submitted to the Town prior to
acceptance of plans for building plan check. The Town Geologist shall
review and comment on the proposed groundwater monitoring
program prior to implementation.
11. The site drainage associated with the proposed development must
be designed as surface flow wherever possible to avoid
concentration of runoff. The proposed drainage shall be designed
to maintain the existing flow patterns. A private storm drain
maintenance agreement and private storm drain easements for
parcels 1 and 2 shall be approved by the Town and signed by both
property owners prior to acceptance of plans for building plan check.
Final drainage and grading shall be inspected by the Engineering
Department and any deficiencies corrected to the satisfaction of the
Engineering Department prior to final inspection.
Planning Commission
April 26, 1995 `
Lands of Ward /parcel 2
Page 6
12. Any, and all, changes to the existing grading and drainage plan
shall first be approved by the Town Engineering Department. No
grading shall take place during the grading moratorium between
November 1 and April 1 except with prior approval from the City
Engineer. No grading shall take place within ten feet of any
property line except to allow access to Francemont Drive.
13. An erosion and sediment control plan shall be submitted for review
and approval by the Engineering Department prior to acceptance of
plans for building plan check. All necessary erosion control and creek
protection measures shall be in place to the satisfaction of the
Engineering Department prior to issuance of any building permits. The
contractor and the property owner shall comply with all
appropriate requirements of the Town's NPDES permit relative to
grading and erosion/sediment control. Any areas on the site that
have the native soil disturbed shall be protected for erosion control
during the rainy season and shall be replanted prior to final
inspection.
14. All public utility services shall be undergrounded.
15. The location, elevation and height of the new residence, decking,
driveway and pool shall be certified in writing by a registered civil
engineer or licensed land surveyor as being in the locations,
elevations and heights approved by the Town and as shown on the
Site Development Plan.
16. The existing type IIB pathway on Francemont Drive shall be
rehabilitated and the driveway shall be roughened where it
intersects the pathway. This work shall be done to the satisfaction
of the Town Engineering Department prior to final inspection. A
pathway easement shall be dedicated to the Town along the portion
of the property between Adobe Creek and Moody Road as shown
on the attached sheet. The applicant shall have the legal
description and plat exhibits prepared by a registered civil engineer
or licensed land surveyor and the Town shall prepare the grant
document. The applicant shall submit the signed and notarized
document and exhibits to the Town prior to acceptance of plans for
building plan check.
17. All subdivision improvements for the Bellucci Subdivision (Parcel
Map No. 608 M 31, 32 & 33 and Tract Map No. 8207) and the
Francemont Subdivision (Parcel Map No. 606 M 14 & 15) shall be
constructed and approved by the City Engineer prior to acceptance of
fans for building plan check.
i
Planning Commission
April 26, 1995
Lands of Ward/parcel 2
Page 7
18. A map revision, or other suitable method for amending the flood
insurance rate map, shall be obtained for this property prior to final
approval.
19. The Lambert Sanitary Sewer Reimbursement Agreement in the
amount of $2,046.56 shall be paid to the Town prior to acceptance of
plans for building plan check. The new residence shall connect to
sanitary sewer service prior to final approval.
20. All construction debris and other deleterious materials shall be
removed from the project site, to the satisfaction of the Engineering
Department,prior to acceptance of plans for building plan check.
21. This property (Parcel No. 2) shall be included in a landslide
maintenance agreement which sets forth maintenance and
monitoring responsibilities as well as any other requirements
deemed appropriate by the Town. This agreement shall be
approved by the Town and signed by the applicant and all
necessary property owners prior to acceptance of plans for building
plan check.
22. Santa Clara Valley Water District (S.C.V.W.D.) has approved the
proposed improvements for this project per a letter from Richard
M. Anderson, dated December 20, 1994. All conditions of the
S.C.V.W.D. permit shall also become conditions of this site
development permit. A copy of the permit issued by S.C.V.W.D.
shall be submitted to the Town prior to acceptance of plans for building
plan check.
23. Upon completion of the construction, a final inspection shall be
required to be set with the Planning and Engineering Departments
two weeks prior to final building inspection approval.
Planning Commission •
April 26, 190
Lands of Ward/parcel 2
Page 8
CONDITION NUMBERS 2, 4, 9, 10, 11, 13 17, 20, 21 AND 22 SHALL BE
COMPLETED AND SIGNED OFF BY THE PLANNING DIRECTOR AND
THE CITY ENGINEER PRIOR TO ACCEPTANCE OF CONSTRUCTION
PLANS FOR PLAN CHECK BY THE BUILDING DEPARTMENT.
EROSION CONTROL AND CREEK PROTECTION MEASURES SHALL BE
INSPECTED AND APPROVED BY THE ENGINEERING DEPARTMENT
PRIOR TO I6SUANCE OF BUILDING PERMITS.
Properties 'r siding within the Los Altos School District boundaries must pay
School Distiict fees before receiving their building permit from Los Altos
Hills. The aiplicant must take a copy of Worksheet#2 to both the elementary
and high school district offices, pay the appropriate fees and provide the Town
with a copy of their receipts.
NOTE: The Site Development permit is valid for one year from the approval
date (until April 26, 1996). All required building permits must be obtained
within that )ear and work on items not requiring a building permit shall be
commenced within one year and completed within two years.
_ '•
330 Village Lane
`William Cotton Los Gatos, California 95030
�, and •Associates (408) 354-5542
December 19, 1994
L3284
TO: Suzanne Davis
Planner
TOWN OF LOS ALTOS HILLS
26379 Fremont Road '\
Los Altos Hills, California 94022
SUBJECT: Geologic and Geotechnical Review -
RE: Ward,Parcel 2-Adobe Creek Subdivision
Francemont Drive
File #202-94-ZP-SD-GD
At your request, we have completed a geologic and geotechnical review of
applications for proposed site residential development using:
• Soil Report prepared by Nielsen Geotechnical,dated November 16, 1994;
• Site Development Plans (Sheets Al, CI, A2, A3 and A4) prepared by
Woodson/Barksdale Architects and Giuliani& Kull,dated November 17,
1994;
• Report on the Consultation for the Adobe Creek Subdivision,prepared by
Jo Crosby & Associates, dated February 2, 1993;
• Engineering Geologic Investigation (report) for Parcels 1, 2 and 3
Francemont Estates, prepared by Louis A. Richardson, dated July 31,
1992; and
• Geotechnical Engineering Evaluation (report) prepared by William
McMorrow, dated August 20, 1992.
In addition, we have reviewed pertinent technical documents from our office files
(Adobe Creek Subdivision L1456 and Menlo Development L3312) and completed a recent
site reconnaissance.
DISCUSSION
The applicant proposes to construct a single family residence and swimming pool in
the central portion of Parcel 2 of the Adobe Creek Subdivision/Francemont Estates. The
southern edge of the house is located immediately adjacent to the toe of a large Dormant
Landslide. We previously reviewed a proposed development application for this parcel
(review report dated September 17, 1992) and recommended that site development not be
approved until a scope of groundwater monitoring and remediation,necessary to ensure the
stability of the adjacent Dormant Landslide, was satisfactorily defined.
Our Adobe Creek Subdivision review report dated March 12, 1993 addressed
details of a recommended groundwater monitoring program, and future dewatering
measures that may need to be implemented to ensure the stability of the Dormant
Landslide. We recommended that a formal monitoring and mitigation program be
established prior to issuance of grading or building permits on individual lots. We
ENGINEERING GEOLOGY • ENVIRONMENTAL EARTH SCIENCES • FOUNDATION ENGINEERING
Suzanne Davis December 19, i994
Paget L3284
understand that three groundwater monitoring wells have been installed within the
landslide.
SITE CONDITIONS
The subject property is generally characterized by gentle to moderately steep (2° to
15° inclination), hillside (Dormant Landslide) and valley floor topography. Approximately
2 to 7 feet of recently placed fill is present over most of the parcel. The referenced July 1992
report by Louis A. Richardson concluded that fill at the property came from several
different sources, was highly variable in consistency, contained debris such as wood,
concrete an old car parts, and should not be considered an engineered unit. The referenced
November 1994 soil report by Nielsen Geotechnical concludes that the current fill on Parcels
1, 2 and 3 is well compacted based on the results of 9 exploratory borings. Wood or other
debris was not encountered in these borings. It is our understanding,based on information
provided by John Nielsen (personal communication on December 12, 1994), that site fills
have been reworked by large grading equipment since 1992.
Site fill materials are underlain by deep unconsolidated alluvial deposits (gravel,
sand silt and clay). The July 1992 report by Louis Richardson concluded that anticipated
ground shaking could produce differential compaction of these underlying deposits. A
portion of a large Dormant Landslide is located in the southwestern portion of Parcel 2.
The potentially active trace of the Berrocal fault has been mapped approximately 500 feet
northeast of the subject property.
The referenced consultation report by Jo Crosby and Associates concludes that the
Dormant Landslide has the potential for renewed movement and the stability of this feature
is very sensitive to the level of groundwater. The consultant concludes that the site is safe
for development (i.e., with respect to deep landsliding) if groundwater levels-do not rise
above the elevation of the lower building pad levels within the landslide mass. However,
this evaluation Was prepared without knowledge of the currently proposed development
plan which sites the house immediately adjacent to the landslide toe.
Current FEMA maps indicate that the proposed house site is located within the
limits of the 100-year flood along the adjacent Adobe Creek. We have not received
documentation to verify what extent of channel improvement or additional fill at the
building pad (if any)may be required to address potential flooding hazards.
CONCLUSIONS AND RECOMMENDED ACTIONS
Proposed site development is constrained by potential landsliding, potential
flooding, undocumented fill, expansive soils, anticipated strong to violent seismic shaking
and the potential for seismically induced differential compaction of the underlying alluvial
deposits.
The proposed development plan, with a portion of the house located immediately
adjacent to the toe of the Dormant Landslide,may result in the residence being particularly
sensitive to any incremental movement (i.e., such as minor lurching in response to seismic
loading) of the landslide deposit. The geotechnical consultant (Jo Crosby and Associates)
that analyzed th'e stability of the Dormant Landslide should evaluate whether it is
appropriate to site a house directly against the toe of the slope as currently proposed, or
whether a nominal setback would be prudent.
William Cotton and Associates
•
Suzanne Davis December 19, 1994
Page 3 L3284
Based on our review of the latest project soil report by Nielsen Geotechnical, it
appears that existing fill conditions can be adequately addressed by current foundation
recommendations. The potential impacts of seismically induced differential compaction
should be specifically addressed by the current project geotechnical consultant. The
adequacy of foundation design recommendations must be re-evaluated if any creek channel
modifications, or placement of additional site fill, is needed to address flood conditions.
The applicant should be fully aware of the potential for cracking of asphalt and concrete
paving at this site as stated on page 14 of the referenced soil report by Nielsen Geotechnical.
Our current review does not include approval of specific geotechnical design for the
swimming pool. Design criteria for the pool should be addressed after development of final
site grading plans.
Any necessary improvements to the Adobe Creek channel should meet requirements
of the Santa Clara Valley Water District and be reviewed and approved by them and the
Town Engineer.
Formal organization of a groundwater monitoring and mitigation program should be
completed prior to issuance of building or grading permits. One of the two annual well
inspections for the Dormant Landslide should be completed in the months of February or
March when groundwater levels are likely to reach their high point. The existing three
monitoring wells within the landslide should be equipped with locking caps and
appropriate protective barriers to prevent accidental damage or vandalism to the well
heads.
If creek improvements do not encroach in a significant manner toward the house site,
then the proposed development plan appears feasible with the implementation of
appropriate engineering design measures. However,we recommend that the following items
be satisfactorily addressed prior to issuance of permits for residential construction:
1. Flood Evaluation-Any necessary improvements to the Adobe Creek channel,or
changes to the building pad elevation,should be reflected on the grading plan for
Parcel 2. The depth of fill and proximity of final creekbanks to the house
footprint may impact proposed residential foundation design criteria. Channel
improvements should meet requirements of the Santa Clara Valley Water District
and be reviewed and approved by them and the Town Engineer.
2. Evaluation of the Proposed House Location - Specific house sites had not been
determined in February 1993 when Jo Crosby and Associates completed the
stability analysis of the Dormant Landslide. The currently proposed
development plan, with a portion of the house located immediately adjacent to
the toe of the Dormant Landslide, may result in the residence being particularly
sensitive to any incremental movement (such as minor lurching in response to
seismic loading) of the landslide deposit. Jo Crosby and Associates should
evaluate whether it is appropriate to site the house up against the toe of slope as
currently proposed,or whether a nominal setback would be necessary.
The results of this evaluation should be submitted to the Town for review by the
Town Geotechnical Consultant prior to issuance of building or grading permits.
3. Supplemental Geotechnical Evaluations - It is important that the project
geotechnical consultant (Nielsen Geotechnical) be informed of any additional fill
requirements or encroachment of creekbanks toward the house site that may
William Cotton and Associates
Suzanne Davis December 19, 1994
Page 4 L3284
result from required flood mitigation. After resolution of flooding issues, the
consultant should review any modifications to the site grading plan and evaluate
whether foundation design criteria adequately address the proximity, and the
potential for long-term instability, of local creek banks. The issues of potential
seismically induced differential compaction,presented in the July 1992 report by
Louis Richardson, should also be addressed. Estimates of total and differential
settlement should be provided. The consultant should verify that proposed lot
gradients and drainage design reflect the intent of recommendations by Jo Crosby
and Associates (report of February 2, 1993) to reduce the infiltration of surface
water.
The results of these supplemental evaluations should be submitted to the Town
for review by the Town Geotechnical Consultant prior to issuance of building or
grading permits.
4. Formal Organization of Monitoring Program - The groundwater monitoring
program descriptions of possible future mitigation measures,drainage easements
and property assessments for the Dormant Landslide should be established to
the satisfaction of the Town utilizing the concepts outlined by Jo Crosby and
Associates. In addition, we recommend that one of the two annual well
inspections be completed in the months of February or March when relatively
high groundwater conditions may prevail. The monitoring program should be
established prior to issuance of grading or building permits for development on
individual lots. We suggest that the applicant install locking caps and protective
barriers as soon as possible at the existing three wells to reduce the potential for
damage.
We recommend that the Town geotechnical Consultant be provided an opportunity
to review specific requirements of the proposed monitoring program prior to
implementation.
Respectfully submitted,
WILLIAM COTTON AND ASSOCIATES,INC.
TOWN GEOTECHNICAL CONSULTANT
Ted Sayre
Senior Engineering Geologist
CEG 1795
Pa trick O. Shires
Principal Geotechnical Engineer
GE 770
POS:TS:rb
William Cotton and Associates
William Cotton 330 Village Lane
Cotton Los Gatos, California 95030
and Associates (408) 354-5542
>>
-'.--.6,///6-..e/larch/. 8, 1995
BAR 0 L3274
TowNO
F7.OS995 L3304
ACT08
444
TO: Susan Manca
Planner
TOWN OF LOS ALTOS HILLS
26379 Fremont Road
Los Altos Hills, California 94022
SUBJECT: Supplemental Geologic and Geotechnical Review
RE: Ward, 202-94-ZP-SD-GD, Parcel 1
Ward, 203-94-ZP-SD-GD, Parcel 2
Ward, 205-94-ZP-SD-GD, Parcel 3
Adobe Creek Subdivision
Francemont Drive
At your request, we have completed supplemental geologic and geotechnical
reviews of the subject applications for proposed site residential development using:
• Supplemental Geotechnical Information (report) prepared by
Nielsen Geotechnical, dated February 13, 1995;
• Site Development Plans-Parcel 1 (Sheets Al, Cl, A2 and A3)
prepared by Woodson/Barksdale Architects and Giuliani & Kull,
dated November 17, 1994;
• Site Development Plans-Parcel 2 (Sheets Al, Cl, A2, A3 and A4)
prepared by Woodson/Barksdale Architects and Giuliani & Kull,
dated November 17, 1994;
•
• Site Development Plans-Parcel 3 (Sheets A1-A5, and C1)
prepared by Woodson/Barksdale Architects and Giuliani & Kull,
dated November 17, 1994;
• Report on the Consultation for the Adobe Creek Subdivision,
prepared by Jo Crosby & Associates, dated February 2, 1993; and
• Geotechnical Engineering Evaluation (report) prepared by William
McMorrow, dated August 20, 1992.
ENGINEERING GEOLOGY • ENVIRONMENTAL EARTH SCIENCES • FOUNDATION ENGINEERING
Susan Manca March 8, 1995 ,
Page 2
In addition, we have reviewed pertinent technical documents from our office files
(Adobe Creek Subdivision L1456 and Menlo Development L3292) and completed a
recent site reconnaissance.
DISCUSSION
The applicant proposes to construct a single family residence and swimming
pool on each of the Parcels 1, 2 and 3 of the Adobe Creek Subdivision/Francemont
Estates. We previously reviewed proposed development applications for these parcels
(review reports dated December 19, 1994) and recommended that supplemental flood
evaluations, geotechnical evaluations and formal establishment of a groundwater
monitoring program be completed prior to issuance of grading or building permits on
individual lots. We currently understand that the Santa Clara Valley Water District is
not requiring additional imWrovements to the Adobe Creek channel to address potential
flooding issues.
The referenced consultation report by Jo Crosby and Associates concludes that
the Dormant Landslide extending into the southern portions of the three parcels has the
potential for renewed movement and the stability of this feature is very sensitive to the
level of groundwater in the hillslope. The consultant concludes that the site is safe for
development (i.e. with respect to deep landsliding) if groundwater levels do not rise
above the lower building pad levels within the landslide mass. The consultant
recommends that ithe three existing wells within the landslide be monitored on a regular
basis and dewatering measures be implemented to control the groundwater if monitoring
wells indicate rising water levels.
CONCLUSIONS AND RECOMMENDED ACTIONS
The request for supplemental geotechnical evaluations in our previous review
has been satisfactorily addressed by the referenced report by Nielsen Geotechnical.
However, formal organization of a groundwater monitoring and mitigation program
should be completed prior to issuance of building or grading permits. As a minimum,we
recommend thatannual well inspections for the Dormant Landslide be completed in the
months of January and March/April when groundwater levels are likely increasing or
have reached their high point. A reading in January may point out the need for initiation
of dewatering before critical levels are reached later in the rain season. The existing three
monitoring wells within the landslide should be equipped with locking caps and
appropriate protective barriers to prevent accidental damage or vandalism to the well
heads.
We recommend geotechnical approval of the subject applications for proposed
construction on Parcels 1, 2 and 3 with the following conditions:
1. Swimming Pool Design - Geotechnical design criteria for proposed
swimming pools should be updated, as necessary, after the project
geotechnical consultant has observed the drilling of foundation piers for
proposed residences. Design criteria for pool shells should be re-
evaluated if unanticipated adverse subsurface conditions are identified.
William Cotton and Associates
Susan Manca March 8, 1995
Page 3
The use of pressure-relief valves should be considered for all proposed
swimming pools. A letter from the project geotechnical consultant
addressing recommended pool design criteria should be submitted to the
Town for appropriate technical review prior to issuance of building
permits for pool construction.
2. Formal Organization of Monitoring Program - The groundwater
monitoring program, descriptions of possible future mitigation measures,
drainage easements and property assessments for the Dormant Landslide
should be established to the satisfaction of the Town utilizing the
concepts outlined by Jo Crosby and Associates. As a minimum, annual
well inspections for the Dormant Landslide should be completed in the
months of January and March/April. The monitoring program should be
established prior to issuance of grading or building permits for
development on individual lots. We suggest that the applicant install
locking caps and protective barriers as soon as possible at the existing
three wells to reduce the potential for damage.
We recommend that the Town Geotechnical Consultant be provided an
opportunity to review specific requirements of the proposed monitoring
program prior to implementation.
3. Parcel 3 Drainage Improvements - As recommended by the project
geotechnical consultant, the two narrow unpaved access roads directly
south of Parcel 3 should be cleaned of forest debris and fine-graded so
that these roads serve as interceptor benches that direct runoff to
Francemont Drive (rather than onto Parcel 3). The consultant shall
confirm that these measures have been adequately completed prior to
final (as-built) approval of improvements on Parcel 3.
4. Geotechnical Plan Review - The applicant's geotechnical consultant
shall review and approve all geotechnical aspects of the detailed building
and grading plans (i.e., site preparation and grading, site drainage
improvements and design parameters for foundations and driveway) to
ensure that his recommendations have been properly incorporated.
The results of the plan review should be summarized by the geotechnical
consultant in a letter and submitted to the Town Engineer for review and
approval prior to issuance of building permits for residential construction
on individual parcels.
5. Geotechnical Field Inspection - The geotechnical consultant shall
inspect, test (as needed), and approve all geotechnical aspects of the
project construction. The inspections should include, but not necessarily
be limited to: site preparation and grading, site surface and subsurface
drainage improvements, and excavations for foundations and retaining
walls prior to the placement of steel and concrete. The consultant shall
inspect the drilling of a representative number of foundation piers on
each lot and document the materials encountered. The final depths of all
piers should be documented. This data should be included in the final
as-built inspection report.
William Cotton and Associates
Susan Manca March 8, 1995
Page 4
The results of these inspections and the as-built conditions of the project
shall be described by the geotechnical consultant in a report and
submitted to the Town Engineer for review prior to final (as-built) project
approval1
Respectfully submitted,
WILLIAM COTTON AND ASSOCIATES, INC.
TOWN GEOTECHNICAL CONSULTANT
Ted Sayre
Senior Engineering Geologist
WL .
William R.Cotton
Principal Engineering Geologist
CEG 882
WRC:TS:rb
•
•
William Cotton and Associates
•
•
Santo GoroValley Water(Astrid
SCI z t,Lk?. I /4-1-'14- i11"-SCS-C ) 5750 ALMADEN EXPRESSWAY
SAN LOSE, CA 95115.83686
caCM. ►.. . 2 202,-`214,---ii,i, �- R:600
FACSIMILE ( )266.0271
re"-rdelt41-,14T trZ(" AN A FIRMATIVE ACTION MPLOYER
RECEIVED
December 20, 1994 .
DEC 211994
Ms. Susan Roberts TOWN OF LOS ALTOS HILLS
Giuliani & Kull, Incorporated
20431 Stevens Creek Boulevard, Suite 230
Cupertino, CA 95014
Oa'
Dear Ms, Roberts: •
The District has reviewed the improvement plans for the development of two parcels( Ns 351-
37-009 and OW), located south of Moody Road and west of Francemont Drive, received by us
on December 15, 1994.
The proposed const ction is acceptable to the District.We will need final plans for issuance of
a permit.
•
Two sets pf final improvement plans should be sent for our review and issuance of a permit prior
to the start of construction.
Any questions may be referred to me at(408) 265-2607, extension 2319.
Sincerely,
'F"•r
Richard M. Anderson
Assistant Engineer
Design Coordination Division
y
Town of Los Altos Hills :,
1/2 5/9 5
To: Planning g Commission & Staff
From: Les Earnest, Pathways Committee Chair
Subject: Pathway requests
12800 Clausen Court; Lands of Jabbour: Restore II-B path along
Voorhees Drive and Clausen Court if damaged during construction.
27781 Edgerton Road; Lands of Shockley: No request.
Parcel 1, Francemont Drive; Lands of Ward: Construct II-B path along
Francemont Dive and Moody Road.
Parcel 2, Francemont Drive;Lands of Ward: Regrade the old lodge
entrance road ' o that it drains into Adobe Creek instead of forming -a
pond. Provide a native path easement over that route, next to Adobe
Creek. Construct II-B path along the rest of the Moody Road frontage.
Parcel 3, Francemont Drive; Lands of Ward: Construct Il-B path along
Francemont. To the extent that it lies within the property, provide a 12
foot easement for the existing path from the end of Francemont
diagonally uphill to join the dirt road that loops through the back of the
lot. Pathway easements should continue-in both directions on this road.
If it is to be a fire road, as seems sensible, a wider easement would be
appropriate for this segment.
13981 Fremont Pines Lane; Lands of Abramo: Construct II-B path along
Fremont Road and Fremont Pines Lane.
26370 Ginny Lane; Lands of Hong: No request
27935 Roble Blanco; Lands of Noghrey: No request.
26010 Torello Lane; Lands of Zatparvar: Construct Il-B path and adjacent
drainage ditch along Fremont Road.
•
Note: where construction or upgrading of paths to the II-B standard is
recommended, this is to include irrigation at least 5 feet away from path
and a non-slip surface on any crossing driveways. Where there is "no
request:" we recommend that in lieu fees be collected where possible.